Composite self-retaining sutures and method

Abstract

A self-retaining suture comprises a composite filament. The filament has retainers on the surface such that the filament can engage and retain tissue without knots. The filament comprises at least two materials having different properties. A surface material of the filament has properties which enhance the formation, elevation and/or deployment of the retainers. A core material of the filament has properties which enhance the tensile strength of the filament. The surgical filament is thin and flexible and may be used for suturing. Methods for manufacturing the filament and retainers are also described.

What is claimed is: 
     
       1. A surgical suture comprising an elongated filament and a plurality of retainers wherein:
 the elongated filament is a composite filament including, a core portion formed of a first material and a sheath portion formed of a second material;
 the plurality of retainers is formed along and within the sheath; and 
 one of the first material and second material shrinks relative to the other of the first and second material thereby causing the plurality of retainers to elevate into a position suitable for engaging a tissue. 
 
 
     
     
       2. The surgical suture of  claim 1  wherein the plurality of retainers is arranged in a bidirectional manner. 
     
     
       3. The surgical suture of  claim 1  where a first end of the filament is attached to a needle, and where a plurality of retainers are arranged such that the suture can be deployed in the direction of the first end but resists movement in the direction of the second end. 
     
     
       4. The surgical suture of  claim 1  wherein the retainers are formed entirely from the second material. 
     
     
       5. The surgical suture of  claim 1  wherein the retainers comprise the second material and some portion of the first material. 
     
     
       6. The surgical suture of  claim 1  having a cross-sectional area, wherein the first material takes up about 25% of the cross-sectional area of the filament, and the second material takes up about 75% of the cross-sectional area. 
     
     
       7. The surgical suture of  claim 1  having a cross-sectional area, wherein the first material takes up about 50% of the cross-sectional area of the filament, and the second material takes up about 50% of the cross-sectional area. 
     
     
       8. The surgical suture of  claim 1  having a cross-sectional area, wherein the first material takes up more than 50% of the cross-sectional area of the filament. 
     
     
       9. The surgical suture of  claim 1  wherein the first material is non-degradable. 
     
     
       10. The surgical suture of  claim 1  wherein second material has a plasticity which comprises 5-90% of a total filament elongation and an ultimately elongation of 10-80%.